Optical fibers provide advantages over conventional communication lines. As such, fiber optic cables are becoming increasingly popular.
For certain applications, fiber optic cables need to pass burn tests that measure flame propagation and smoke generation. Exemplary burn tests are NFPA-262 and UL-910, each of which is hereby incorporated by reference in its entirety. In some fiber optic cable designs, several grades of flame-retardant compounds are used in order to achieve compliance with various cable burn test requirements. In particular, when attempting to make a cable design that will pass a burn test such as NFPA-262, choice of cable materials can substantially affect burn performance.
For example, high burn performance materials such as polyvinylidene fluoride (PVDF) may be used. PVDF materials, however, increase the cost of producing the cable. Polyvinyl chloride (PVC) materials may be used in place of PVDF materials, but cable designs using PVC materials do not perform as well as PVDF materials in burn tests.
To achieve compliant burn test results, jacketing or buffer tube compounds with higher levels of flame retardancy (e.g., PVDF) are typically used. Additionally, flame-retardant barrier tapes may be employed.
In general, it is more costly to use materials (e.g., PVDF) having better performance with respect to flame retardancy and smoke generation. The use of flame-retardant barrier tapes such as NOMEX® tape, adds cost, increases processing complexity, and also creates another structural layer that can complicate cable access.
In view of the foregoing, there exists a need for a fiber optic cable having improved overall cable flammability (i.e., improved flame retardancy and reduced smoke generation) without resorting to high-cost jacketing or buffering compounds or otherwise employing expensive and difficult-to-apply barrier tapes.